Continuous molding machine



July 14-, 1942. w, R WEBSTER 2,290,983

CONTINUOUS MOLDING MACHINE Filed June 4, 1940 2 Sheets-Sheet 1 lNVENTORATTORNEYS Jufiy M 1942 w. R. WEBSTER 3 3 CONTINUOUS MOLDING MACHINEFiled June 4, 1940 2 Sheets-Sheet 2 |l w- M.

lNVENTOFZ fzi-awk B ATTORN EYS.

Patented July 14, 1942 UNITED STATES PATENT OFFICE CONTINUOUS MOLDINGMACHINE William R. Webster, Bridgeport, Conn.

Application June 4, 1340, Serial No. 338,725

2 Claims.

This invention relates to continuous molding machines and moreespecially to machines for molding bars or rods.

A continuous molding machine of the type to which this inventionparticularly applies consists essentially of a tubular molding chamberhaving an inlet and an outlet of which the latter desirably is at alower elevation than the former. Means are provided to introduce moltenmetal into the chamber inlet and means are provided for withdrawing thesolidified metal in bar form from the outlet while means are provided topromote solidification of the metal in its passage through the moldingchamber, such means usually comprising a jacket surrounding the chamberand provided with means for circulatlng coolant therethrough.

Heretofore continuous molding machines have not been satisfactory due tothe lack of uniformity in the molded rods or bars. The lack ofuniformity has been due to the absence of means for closely controllingthe relation of the feed rate of molten metal to the discharge rate ofthe molded bar or rod. If the molded rod or bar is discharged at too lowa rate, the molten metal overflows the mold and if the discharge rate istoo great, then partially solidified metal is discharged instead offully solidified metal. Also, previous continuous molding machines havebeen unsatisfactory due to the occurrence in the molten metal ofso-called cold shots resulting in surface irregularities and have alsobeen un satisfactory due to contact of slag and oxides against the moldsurface with resulting trapping of the same in the solidifying metalcausing surface irregularities. I

An object of this invention is to provide a continuous molding machineequipped with automatic means operative to control the level of themetal in the molding chamber.

A further object of the invention is to equip a continuous moldingmachine with molten metal feeding means of such nature that circulationof the metal is effected at the top of the mold in such manner as tocollect buoyant impurities on the surface of the molten metal in themold, also efiect uniform transition of the metal from its fluid toitssolld state and also direct the entering hot metal rapidlyagainst themold Fig. 4 is an enlarged fragmentary view of a modified molten metalinlet;

Fig. 5 is a section on the line 5-5 of Fi 4;

Fig. 6 is a view similar to Fig. 4 of another modification, and

Fig. 'i is a section on the lin 1-1 of Fig. 6.

In Figs. 1 and 2, I0 is a vertical molding tube or chamber open at itsupper and lower ends and housed within a casing ll constituting a jacketfor circulating cooling liquid around the molding tube. Pipes i2 and I3are provided for supplying and withdrawing the cooling liquid. A pouringbox or dish I is supported above the molding tube II by any suitablemeans (not shown) and is provided with a bridge 15. Preferably, a pipel6 extends from the bottom of the pouring box ll into the molding tubeID a predetermined distance below the top of the molding tube but suchpipe may be dispensed with in which case the metal will flow in anunconfined stream from the box l4 into the mold. Molten metal to be castis delivered from an adjustable furnace ll of the standard inductiontype supported by a shaft l8. Means, well known in the art, but notdisclosed herein are provided for initially forming the ingot blank orstool IS in the mold, an example of such means bein illustrated in thepatent to Williams, No. 2,079,- 644. The ingot I9 is withdrawn from themold tube by any suitable extracting or withdrawing mechanism such, forexample, as toothed rollers 20 which engage the surface of the ingot.

The rollers 20 are operated in synchronism by a driving screw 2|provided at one end with a gear 22 which meshes with a pinion 23 mountedon the armature shaft of a motor 24. In the shunt field circuit of themotor 24, a manually adjustable rheostat 25 is connected in series witha manually adjustable rheostat 2B. The armature 21 of a relay 28 isconnected in shunt to I the rheostat 26. A contact member 29 which maybe a small electrical carbon is carried by an insulated support 30 andis part of a circuit including the coil of the relay 28, both ends ofsuch circuit being grounded. Power is supplied to the relay circuit bythe transformer 3|.

The height of the molten metal in the mold I0 is controlled bycontrolling the speed of rotation of the rollers 20. The arrangement ofthe rheostats 25 and 26 is such that when the rheostat 2G isshort-circuited by the armature 2'! of the relay 28, the motor operatesat a slower speed than when the rheostat 26 is not short-circuited.Whenever the level of the molten metal in the chamber I II is such thatthe metal engages the contact 29, the relay is energized to operate thearmature 21 to open the shunt circuit around the rheostat 26, therebyspeeding up the rollers 20 with consequent faster withdrawal of metalfrom 0 the molding tube and reductionof the height of the metal in themolding chamber is disengaged from the contact 29 whereupon the relaycircuit is broken with the result that the armature 21 closes the shuntcircuit around the rheostat, thereby short-circuiting the same andcausing a decrease in the rotational speed of the rollers withconsequent slower emergent speed of the bar iii. The rheostats and 23are manually adjustable so as to normally make the speed of the motor 24and the rollers 2| such that the rise and fall of the metal level in themold does not take place with too great frequency or amplitude. Also,the rheostats may be so adjusted as to cause cyclical rise and fall ofthe metal in the mold over a predetermined distance.

The shaft I3 of the furnace Il carries a gear 32 which meshes with aworm 33 carried by the shaft 34. The shaft 34 is driven by variablespeed means 35 of the type shown in Webster application, Serial No.221,925. A contact 36 is supported for engagement by the metal in thedish l4 and is electrically connected to control apparatus 31 effectiveto vary the speed of one of the motors of the variable speed means 35,

thereby causing faster or slower rotation of the worm 33. With thisarrangement, the level of the molten metal in the dish i4 is maintainedsubstantially constant. Upon decrease of the level of molten metal inthe dish l4 sumcient to disengage the metal from the contact 38, therotational speed of the worm 33 is increased to tilt the furnace I! toincrease the rate of flow of the molten metal into the dish, therebycausing a rise in the level of the molten metal. Upon re-engagement ofthe molten metal with the contact 36, the reverse procedure is, effectedwith consequent maintenance of approximately constant level of metal inthe dish. The control means may alternatively be of the same type as thecontrol means for the rollers 2|.

The outlet from the dish I4 is on the opposite side of the bridge l5from that into which the molten metal is introduced so that the bridgeskins off any dross or foreignmatter which may be introduced into thedish from the furnace. 4

As shown in Fig. 2, a flanged bushing 38 is screwed into the lowerportion of the pouring dish l4 and a worm gear 39 is rotatably supportedby said bushing. A bracket 40 attached to the under face of the wormgear 39 is rigidly attached to and support the tube I6, at the lower endof which are provided a plurality of radial vanes 4i. A worm 42 mesheswith the worm gear 39 and is driven by any suitable means (not shown).The tube l6 extends sufficiently below the level of the molten metalthat the ribs 4| are completely immersed in such metal. The tube I6 iscaused to rotate during the introduction of molten metal into the tube,thereby causing horizontal rotary circulation of the molten metal nearthe upper level thereof.

In the modification shown in Figs. 4 and 5, the tube l 6 has its upperend rigidly connected to the pouring dish l4 and at its bottom end isprovided with a plurality of radial apertures 43 and a collar 44 isrotatably supported by the tube in overlying relationship to the ports43. The collar is equipped with a plurality of nozzles 45 substantiallytangential to the surface of the tube i6. Molten metal escape from thetube l3 partly through the bottom outlet and partly through the nozzles45, causing rotation of the collar 44 with consequent distribution ofthe incoming metal over the entire mold tube area. The flow of moltenmetal from the nozzles 45 causes rotary horizontal circulation in theupper portion of the molten metal.

In Figs. 6 and '7 is disclosed a modification in which the tube I3 isprovided with tangential 5 horizontally directed orifices 48 adjacentthe bottom of the tube. The flow of molten metal through the orificescauses horizontal rotary circulation of the metal in the mold tube.

The horizontal rotary circulation of the upper portion of the moltenmetal in the mold tube distributes the incoming metal uniformly over thesurface of the mold tube'and causes the light particles of dross andoxide floating on the top surface of the metal to approach the center ofthe surface of the body of metal. Segregation of such particles at thecenter of the metal surface permits the removal thereof by any suitablemeans, and also prevents such particles from becoming incorporated inthe surface of 20 the metal bar. Also, the horizontal rotatingcirculation of the top portion of the body of molten metal preventsoccurrence of so-called cold shots and similar surface irregularities aswell as effects uniform transition of the metal from its liquid to itssolid state.

The mold tube l0 may be composed of brass and in a machine for castingbrass, a lining of chromium tungsten or the like is preferably providedfor the tube Ill. The use of such a lining obviates all tendency forzinc oxide to adhere to the surface of the mold tube, thereby avoidingmalfunction of the apparatus due to zinc oxide sticking to the inside ofthe mold as has been the case where the inner surface of the mold wasbrass.

I claim: 1. A continuous molding apparatus comprising a vertical moldingchamber having a top inlet and a bottom outlet, a pipe leading into saidchamber, means rotatably supporting said pipe at its upper end,. meansfor supplying molten metal to the upper end of said pipe, means forpromoting solidification of the molten metal in said chamber, means forwithdrawing solidified 5 metal from said chamber through said outlet, 9.driving motor for said withdrawing means, a contact in the upper portionof said chamber engageable by molten metal therein, an electric circuitclosed by engagement of the metal with v said contact, means controlledby the amount of current flow in said circuit for regulating the motorspeed, means for effecting rotation of said pipe and agitating meanscarried by the lower end of said pipe.

2. A continuous molding apparatus comprising a vertical molding chamberhaving a top inlet and a bottom outlet, a pipe leading into the upperend of said chamber, means rotatably supporting said pipe at its upperend, means for sup- 00 plying molten metal to the upper end of saidpipe, means for effecting rotation of said pipe, agitating means carriedby the lower end of said pipe, for effecting horizontal circulation ofthe upper portion of the metal in said chamber,

means for withdrawing solidified metal from said chamber through saidoutlet, and means responsive to the height increase of the molten metalin said chamber to decrease the ratio of the molten metal flow rate tothe linear longitudinal speed of the metal discharged from said chamberand responsive to height decrease of molten metal in said chamber toincrease the ratio of the molten metal flow rate to the linear emergentspeed of the solidified metal.

WILLIAM R. WEBSTER.

